Werner siemens



' (No Model.)

W. SIEMENS. PROCESS OF ELEOTRO DEPOSITION 0P METALS.

No. 415,576. Patented Nov. 19,1889.

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UNITED STATES PATENT OFFICE.

IVERNER SIEMENS, OF BERLIN, GERMANY, ASSIGNOR TO SIEMENS otHALSKE,

OF SAME PLACE.

PROCESS OF ELECTRO-DEPOSITION OF METALS.

SPECIFICATION forming part of Letters Patent No. 415,576, dated November19, 1889.

Application filed April 11, 1887. Serial No. 234,446. (No specimens.)Patented in Italy October 30, 1886, No. 20,638, and in Spain November29,1886, No. 10,139.

To aZZ whom, it may concern:

Be it known that I, WERNER SIEMENS, of Berlin, a subject of the King ofPrussia, residing at Berlin, in the German Empire;

' have invented certain new and useful Improvements in the Process forthe Electro- Deposition of Metals, (for which I have obtained a patentin Italy, No. 20,638, bearing date October 30,1886, and in Spain, No.10,139, dated November 29,1886,) of which the following is aspecification.

Hitherto it has been usual in the electrolytical extraction of metals touse as anodes plates of the metal to be obtained, which plates wereprepared by smelting ores containing the metal, and thus they containedmany of the impurities of the ores from which they were cast, notablyiron. When these plates were submitted to the action of the electriccurrent and electrolytic solution, the metal to be extracted and theiron were both dissolved out of them, and the copper thus obtaineddeposited in a metallic state at the cathode, whereby the electrolyticsolution had to be replaced by a fresh one and the anodeplatesdissolved; but, in addition to these, the anode-plates oftendisintegrated before their complete dissolution. In these cases it willbe seen that there are three principal causes of expense andtroubleviz., the preparation of a new electrolytic solution from theore, the preparation of. new anodeplates, also from the ore, which wasoften difficult and uncertain, and the disintegration of the plates whenformed.

My invention has for its object to obviate these difficulties; and itconsists in the following process: subjecting a solution of a salt ofthe metal which it is desired to obtain and of a ferrous salt to theaction of a cathode-plate, whereby the desired metal will be depositedand the element or elements in chemical com- .bination therewith will beliberated; subjecting the outflowing liquid to the action of ananode-plate of insoluble material-such as carbon, platinum, or lead, orof a plate covered with platinumthe said cathode-plate being separatefrom the anod e-plate by a nonmetallic diaphragm which is impervious tothe solution, but which allows the electric current to pass, whereby thefree elements liberated by the cathode-plate will be caused to enterinto chemicalcombination with the ferrous salt, converting the latterinto a fer ric salt, and, finally, lixivaiting ore containing the metalto be extracted with the solution of the ferric salt obtained from theanode-plate, whereby the metal will be dissolved and the ferric saltreconverted to a ferrous one, and a solution obtained with the samechemical constituents as that first passed under the influence of thecathode-plate, or, instead of subjecting the electrolytical solution tothe action of a single pair of plates only, several anode and cathodeplates may be used, and the solution subjected successively to each, aswill be hereinafter more fully described and claimed.

Referring to the accompanying drawings, which represent apparatussuitable for use in carrying out my invention, and in whichcorresponding parts are designated by similar letters, Figure l is avertical section of a single cell, and Fig. 2 is a vertical section of aseries of cells in which the liquid passes from the compartments of theone to the other.

B, Fig. 1, represents a cell in which a nonmetallic diaphragm D isplaced, having near the upper edge of the cell a mouth R, through whichthe liquid in the outeror cathode compartment B may flow into the inneror anode compartment B when it has reached its level. The diaphragm D,which is constructed of a substance impervious to the electrolyticalliquid, but through which the electric current may pass, is suspended inthe cell B by means of beams 13 preferably of wood. The funnel B has itsdowntake B extending to near the bottom of compartment 18. The plate Kis suspended in the same compartment from the beam 13, similar to beamsB the plate being connected with the negative pole of a source ofelectricity, and thus form ing the cathode-plate. In the compartment Bis suspended the plate A, of carbon, platinum, lead, or other insolublematerial, or a plate covered with platinum, the plate being connectedwith the positive pole of the source of electricity and suspended fromthe beam B thus forming the anode-plate. The arm 0 of the siphon M,which rises over the edge of the cell, extends to the bottom ofcompartment B and has a neck C on the outside of the cell, the said neckextending below the level of the mouth R of the diaphragm D, while thelevel of the outlet C of the siphon is on aslevel therewith, whereby,the siphon, when once" filled with the contents of compartment B isprevented from drawing off its contents below the level of the mouth R,and the upper part C of the siphon prevented from becoming filled withair, which would prevent its action.

When the electrolytioal solution is to be subjected to the action ofseveral cells successively, the apparatus represented in Fig. 2 is used.In this construction the cells E E E &c., are placed in series, thefirst cell E being at a greater height than the succeeding one. In eachof these cells is a non-metallic diaphragm D, inclosing thecathodecompartment K while the anode-compartment A surrounds the saiddiaphragm. The anode-compartment contains the anode-plate A, while thecathode-compartment contains the cathode-plate K, as has already beendescribed in relation to the construction of a cell adapted for separateuse. Funnels A and K are provided for the anode and cathodecompartments, respectively, of the first or upper cell E, the downtake aof the funnel A extending only a small distance below the level of thetop of the liquid in the anodecell, while the downtake extends to nearthebottom of the cathode-compartment. A siphon K rises from near the topof the liquid in the cathode-compartment K of each cell, and, afterforming a neck k, ends in the cathode-compartment of the next succeedingcell. The height y of the neck 7i) is by preference equal to thedifference of height 2 between the successive cells. A siphon A similarto K, rises from near the bottom of the anode-compartment A of each ofthe cells, and, after forming a neck a, ends in the anode-compartment ofthe succeeding cell. By means of the necks a and 7c the upper bends aand 7c of the siphons are kept constantly filled, and the liquids ineach of the cells is prevented from falling to a lower level than thatof the upwardly-opening ends a and 70 of the siphons A and K, whichterminate in the succeeding cell.

In the use of the apparatus illustrated in Fig. 1 a liquid containingthe metal to be extracted and a ferrous salt is slowly but continuouslyfed through the funnel l3 and downtake B into the bottom of thecathode-compartment B, where, yielding up the desired metal to thecathode-plate, it becomes lighter, and, rising along the plate, depositsstill more of its metallic contents thereon, and finally passes overmouth B into the anode-chamber B where the liquid is subjected to theaction of the anodewill be hereinafter described, and the con vertedliquid, which will have become heavier, will sink to the bottom of thecompartment and be drawn off by the siphon M.

In the apparatus shown in Fig. 2 the operation is as follows: Theelectrolytical solution is fed down the funnel K and downtake k to thebottom of the oathode=compart1nent of the upper cell E, Whereit will, asin the previous case, become lighter by deposition of the metal which itis desired to extract, and, flowing upward, will enter the siphon K andbe drawn by the action thereof into the cathodecompartment of thesucceeding cell, and so continue to pass through thecathode-compartments of as many cells as may be employed, leaving ineach a part of the desired metal. As the ends of the effiux and influxsiphons K of the cathode-compartments K of each of the cells E E 850.,are near its top, the liquid contained in such compartments should beagitated in any suitable manner in order to secure a circulation at thebottom thereof. After the liquid has passed through all thecathode-compartments and is freed from the metal to be extracted it isfed into the upper part of the anode-compartment of the first cell Ethrough the funnel A and downtake a Here it is acted upon by theanode-plates and becomes heavier, sinking and flowing through the siphonA to the top of the anode-compartment of the next cell, where, under thefurther action of the anode-plates contained therein, it becomes stillheavier, and, again sinking, flows to the anode-compartment of the nextcell, until it has passed through the anode-compartments of all thecells.

My invention may be used in several cases,

as will be hereinafter shown. In the first of these it may be desired toextract copper by means of a sulphate solution, in which case the liquidsubjected to electrolysis consists of a solution of ferrous sulphate(FeSOQ and cupric sulphate (CuSO and some free sulphuric acid, (H SOwhich is added to improve its conductivity. The liquid which is used atthe beginning of the operation is formed in any suitable manner, as bydissolving copper and iron in sulphuric acid. This liquid is then ledinto the cathode-compartment of the single cell B or in thecathodecompartment of the first cell E of the series of cellsillustrated in Fig. 2. Here the cupric sulphate is decomposed, thecopperbeing deposited in a metallic state, while the sulphur and oxygenare still contained in the liquid and carried thereby. The solution,becoming lighter by the deposition of a portion of its metalliccontents, rises in the cathode-coinpartment. In case the series of cellsare used, the solution, having passed through the oathode-compartment ofone cell, passes through the corresponding compartments of the othercells until it has passed through the full series and is entirely freedof its copper. The

plate. The chemical action in this chamber liquid after passing throughthe cathode-compartments is fed into the anode-compart' verting thesulphides of copper (CuS and CuS and oxide of copper (CuO) into sulphateof copper. The ore to be treated may consist of copper pyrites, which isfirst pulverized and roasted at amoderate heat (best in a Gerstenhafersfurnace) to such a degree that the iron contained originally in thepyrites is almost entirely oxidized, in which state it is not affectedby the ferric sulphate, while the copper is contained in the roasted orepartly as sulphate of copper, but for the most part as subsulphuret ofcopper, (Ou S.) The ore so prepared is then submitted in suitablelixiviating compartments or vessels to the action of the liquid flowingfrom the anode-compartments. The ferric sulphate contained in the liquidconverts the sulphide of copper and oxide of copper of the prepared oreinto sulphate of copper, which will be taken up into solution, while theinsoluble oxide of iron remains, and the ferric sulphate in acting uponthe ore will be reconverted into ferrous sulphate.

The chemical action occurring in the electrolysis and extraction may beseen from the following equation:

First, occurrence during electrolysis Second, occurrences duringextraction- By comparing formula 1 and 2 it will be perceived that ifthe ore contains all the cop per in the form of subsulphide of copperthe el ectrolytical liquid, after passing through the extractingvessels,will contain precisely the same quantity of sulphate of copper, ferroussulphate, and free sulphuric acid as before the electrolysis, beingregenerated, and is therefore adapted to be again led to the galvaniccells to undergo the same treatment, causing this to be a continuousprocess, in which the same liquid may be used until it has, by absorbingforeign metals from the ore, become too impure for further use in thismanner. The solution when fed into the cathode-compartment may be of anydesired strength, and I by preference employ an electric currentamounting to twenty-five amperes per square meter of the surface of thecathodeplate.

An analogous method for the electrolytical separation of copper is theprocess of chlorinization. The electrolytical liquid then consists ofcuprio chloride (01101,) and ferrous chloride, (FeCl from which in thegalvanic cells copper and ferric chloride (Fe Ol are obtained accordingto the following equation: CuCh-l-QFOh:Qu-l-Fefih.

The ferric chloride thus formed possesses the power of convertingsulphide of copper not decomposed by roasting into cupric chloride,(OuC1 and also of converting, with the aid of a solutionpf chloride ofsodium, (NaOl,) cuprous' chloride (011 01 into cupric chloride. Ineither case ferric chloride is reduced again into ferrous chloride.Thus, also, in this process the solution is regenerated so that itbecomes again suitable for electrolysis, and no polarization takesplace. In the use of anodes consisting of matte of copper a differenceof potential of about 1.5 volts is consumed and about one-third of thecurrent employed in doing other work than that of reduction, and is thuslost, while by the process above described a tension of 0.7 volts, withdouble the density of the current, is sufficient, all of which isemployed in the reduction of the solution. The same process can befurther used for an electrolytical extraction of zinc from sulphurizedzinc ores "with the aid of a solution of sulphate of zinc (ZnSOQ andferrous sulphate.

In the electrolytical cells zinc and ferric sulphate are formedaccording to the following equation:

ZnSO,|2FeSO,- :Zn+Fe (SO,) The ferric sulphate thus formed possesses theproperty to dissolve zinc out -of the slightly-roasted zinc blendes,(ZnS,) and sulphate of zinc and ferrous sulphate are formed according tothe following equation:

ZnS-l-Fe (SO,) :ZnSO,+2FeSO,l-S.

A comparison of this and the preceding equation will show that, afterthe slightly-roasted zinc blendes have been acted upon by the liquid,the amount of iron and zinc therein has become as great as beforeelectrolysis.

An analogous process can be used for the extraction of zinc by means ofa solution of chloride of zinc ZnOl and ferrous chloride. In thisinstance in the electrolytical cells zinc and ferric chloride areformed, which latter can again dissolve zinc out of zinc blendes bybeing reduced to ferrous chloride. Of course in the zinc processes thedifference of potential in the electrical current, must be nearly twiceas great as in r the cop.- per processes above described to overcome thecounter-current created by the tension between the zinc and carbon.

The principle utilized in the process above described is that oxidizablesolutions conducting electricity are oxidized at an anode which consistsof carbon (or even platinum, gold, or lead, &c.)- under certainconditions by the galvanic current to a higher degree than they werebefore without effecting polarization. This principle can also beutilized for other chemical operations by arranging the decompositionapparatus in such a way that in. the cells surrounding the ITO 7 in theelectrical circuit.

In order to cite some examples of chemical operations effected by thisprocess, it may be stated that by it, at a very low expense,

ferric salts can be obtained at the anode plate from ferrous salts,ferric chlorides from ferrous chlorides, ferric cyanides from ferrouscyanides, (for instance, red from yellow prussiate of potash,) while inthe cathodecompartments metals (for instance, copper, iron, zinc) can beprecipitated from the corresponding salts solutions and hydrates ofpotassium or sodium formed, &c.

Having thus described my invention, what I desire to secure by LettersPatent is v 1. The process which consists in lixiviating ore with asolution containing a ferric salt,

subjecting the resulting ferrous solution at the cathode of anelectrolytic'cell to the action of a current of electricity, whereby themetal in solution is deposited, then subjecting the remaining liquid tothe oxidizing action at the anode, whereby the ferrous is reconvertedinto a ferric solution, which solution is again used to lixiviate ore.

2. The process which consists in lixiviating ore in separate vesselswith a solution con= taining a ferric salt, subjecting the resultingferrous solution at the cathode of an electrolytic cell to the action ofa current of electricity, whereby the metal in solution is-deposited,then subjecting the remaining liquid to the oxidizing action at theanode, whereby the ferrous is reconverted into a ferric solution, whichsolution is again used to lixiviate ore.

The process which consists in lixiviating ore in separate vessels with asolution containing a ferric salt, passing the resulting ferroussolution successively through a series of compartments containingcathode-plates, and in which cells the solution is subjected to theaction of an electrical current by which the metal in solution isdeposited, then passing the remaining liquid successively through asecond series of compartments containing anode-plates of insolublematerial and separated from the first-mentioned compartments bynon-metallic diaphragms, whereby the ferrous solution is oxidized andreconverted into a ferric solution, which solution is again used tolixiviate ores.

4. The process which consistsin lixiviating ore with a solutioncontaining ferric sulphate, subjecting the resulting ferrous sulphate atthe cathode of an electrolytic cellto the action' of a current ofelectricity, whereby the metal in solution is deposited, then subjectingthe remaining liquid to the oxidizing ac tion atthe anode, whereby theferrous sulphate is reconverted into ferric sulphate, which solution isagain used to lixiviate ore.

5. The process which consists in lixiviating ore in separate vesselswith a solution containing ferric sulphate, subjecting the resultingferrous sulphate at the cathode of an electrolytic cell to the action ofa current of electricity, whereby the-metal in solution is deposited,then subj ecting the remaining liquid to the oxidizing'action at theanode, whereby the ferrous sulphate is reconverted into ferric sulphate,which solution is again used to lixiviate ore.

6. The process which consists in lixiviating ore in separate vesselswith a solution containing ferric sulphate, subjecting the resultingferrous sulphate at the cathode of an electrolytic cell to the action ofa current of electricity, whereby themetal in solution is deposited,then subjecting the remaining liquid to the oxidizing action at theanode, thesaid anode being separated from the cathode by a diaphragm,whereby the ferrous sulphate is reconverted into ferric sulphate, whichsolution is again used to lixiviate ore.

7. The process which consists in lixiviating ore in separate vesselswith a solution containing ferric sulphate, passing the resultingferrous sulphate successively through a series of compartmentscontaining cathodeplates, and in which cells the solution is sub-.jected to the action of an electrical current by which the metal insolution is deposited, then passing the remaining liquid successivelythrough a second series of compart ments containing anode-plates ofinsoluble material and separated from the first-mentioned compartmentsby non-metallic diaphragms, whereby the ferrous sulphate is oxidized andreconverted in ferric sulphate, which solution is again used tolixiviate ores.

WERNER SIEMENS. Witnesses:

F. VON VERSEN, B. R01.

